Spring type shock absorber for firearms



J. HREBICEK 3,208,179

SPRING TYPE SHOCK ABSORBER FOR FIREARMS Filed March 25, 1963 2 Sheecs-Sheecl l FIGI Sept. 28, 1965 w M F 7 s l I 2 Sept. 28, 1965 J, HREBlCEK 3,208,179

SPRING TYPE SHOCK ABSORBER FOR FIREARMS Filed March 25, 1963 2 Sheets-Sheet 2 milf 55 INVENTOR: JAMES HREBICEK ATTY United States Patent O 3,208,179 SPRING TYPE SHOCK ABSORBER FOR FIREARMS James I-Irebicek, 2'327 61st Ave., Cicero, Ill. Filed Mar. 25, 1963, Ser. No. 267,535 14 Claims. (Cl. 42 74) This invention relates to shock absorbing devices of the coiled spring type and particularly to a spring recoil mechanism such as is used in firearms. The invention is of wider scope than firearms, however, and can be applied to machine tools such as punch presses, assembly fixtures or the like and can also be applied to vehicles, particularly to take the place of the spring suspensions thereof.

For purposes of illustration this invention will be described with reference to its application to the gunstock of a rifle, shotgun or the like. It is known that the discharge of a rifle or a shotgun produces a reaction or a blow against the shoulder of the gunner. To reduce the magnitude of the blow it has been proposed to divide the gunstock vertically and insert a horizontally operable spring between the two gunstock parts. In such proposals, the duration of the blow was increased and its magnitude decreased, but the total reactive energy absorbed by the shoulder remained substantially the same except for that required to compress the spring, and some of this was released against the shoulder as the compressed spring was restored to its original condition.

The principal object of this invention is the provision of a shock .absorbing mechanism which is to be inserted in a frame between that portion of the frame which is subject to an active force and the remainder of the frame which is normally stationary, wherein an appreciable portion of the force is diverted and made to act in a direction transverse to that of the original force, thereby materially reducing the energy required to be absorbed by the stationary portion of the frame.

Another object of this invention is the provision of a spring type recoil mechanism for a gunstock which will not require the alteration of the normal proportions and dimensions of a gun, but which nevertheless will effectively prevent the transmission of a major portion of the recoil from an exploding shell to the shoulder of the gunner.

Further objects include the provision of a recoil mechanism which may be inserted into a standard gunstock and which is adjustable as to the degree of recoil absorption; which is rugged in construction and which, if desired, may be readily removed for cleaning and repair.

These and other objects of this invention will become apparent from the following detailed description of a preferred embodiment of the invention when taken together with the accompanying drawings in which:

FIG. 1 is a side elevational view of a gunstock to which this invention has been applied, with a portion of the stock removed to disclose the recoil mechanism of this invention in a relaxed condition;

FIG. 2 is a view of a gunstock similar to that of FIG. l, but showing the recoil mechanism in another stage of operation;

FIG. 3 is a sectional view of the gunstock in FIG. 1 taken along line 3 3 of FIG. 1 and looking in the direction of the arrows at the ends thereof;

FIG. 4 is a sectional view of the gunstock of FIG. 1 taken along line 4 4 of FIG. 1 and looking in the direction of the arrows at the ends thereof;

FIG. 5 is an enlarged fragmentary elevational view of a portion of the recoil mechanisms showing the method of adjustment thereof;

FIG. 6 is a fragmentary end elevation, on an enlarged scale, of a portion of the recoil mechanism, the view being taken along line 6 6 of FIG. 2 and in the direction of the arrows at the end thereof;

FIG. 7 is a fragmentary plan view on an enlarged scale of the gunstock of FIG. l;

FIG. 8 is a side elevational view of a modification of the recoil mechanism and gunstock of FIG. 1;

FIG. 9 is an enlarged view of a portion of the recoil mechanism of FIG. 8;

FIG. 10 is an enlarged rear elevational view of the mechanism of FIG. 2 taken along line 10 10 thereof; and

FIG. 11 is a displacement-deflection chart for a cam used in the recoil mechanism.

Referring now to the drawings for a detailed description of the invention and particularly to FIG. 1, there is shown a gunstock 10 for a shotgun 11 or the like, said gunstock 10 being comprised of two parts 12 and 13 which may be termed the action and reaction members, respectively, of the gunstock. In the form chosen to illustrate this invention, each part 12 and 13 may be a casting of lightweight material such as aluminum or magnesium and is made hollow to contain the recoil mechanism.

Gunstock part 12 is comprised of a die-cast shell 14 in which are located parallel blocks 15 and 16 (FIG. 3) adjacent the sides 17 and 18, respectively, of shell 14. Said blocks are preferably formed integrally with said shell in the casting process. Between blocks 15 and 16 and extending below to the rounded bottom portion 19 of shell 14 is a cam device 20 having a cam surface 21 of pre-determined form thereon. Said cam device 20 is mounted on a pivot (FIG. 2) in the form of a pin 22 extending transversely through part 12 so as to be accessible from the outside thereof.

The angular disposition of cam device 20 relative to part 12 is determined by a pair of set screws 23 and 24 extending upwardly from the bottom 19 of shell 14 into contact with surfaces 25 and 26, respectively, formed on cam device 20 opposite cam surface 21. It is contemplated that set screws 23 and 24 will be firmly braced against cam device 20 at all times to maintain the desired disposition of the said cam device in part 12.

Part 13 is also a die casting and has spaced blocks 27 and 28 located in the side walls 29 and 30 thereof and preferably formed integrally therewith in the casting process. Said blocks 27 and 28 are aligned with blocks 15 and 16, respectively, and have through bores 31 and 32 through which pass shoulder bolts 33 and 34, respectively. The threaded ends of said bolts engage threaded recesses 35 in blocks 15 and 16 by which said bolts are rigidly held in part 12. Each of said bolts 33 and 34 has a head 36 which limits movement of a block 27 or 28 relative to a bolt 33 or 34 to the right as viewed in FIGS. 1 and 2. Bolts 33 and 34 thus function as guides which permit part 13 to move relative to part 12, and additionally serve to hold parts 12 and 13 in assembled relation.

Part 13 is provided with a cam device 37 having a cam surface 38 of substantially the same curvature as cam surface 21 on cam 20. Said cam device 37 is similarly mounted on a pivot in the form of a pin 39 which passes through aligned openings in spaced bosses 40 and 41 formed in the bottom interior portion of part 13. The disposition of cam device 37 relative to part 13 may be adjusted by a pair of set screws 42 and 43 operating against surfaces 40 and 45 respectively on opposite sides of pivot 39. Said screws are firmly braced against cam device 37 to hold said device in fixed relation to part 13.

Part 13 is open on its righthand side as viewed in FIG. 1 to provide access to the interior thereof for the purpose of assembling shoulder bolts 33 and 34 with 3 respect to the spaced blocks and 16. The open end of part 13 may be closed by a plate 46 which may be fastened to part 13 in any suitable manner. Plate 46 may be surfaced with leather or other soft material if desired (not shown) to suit the individual requirements of the gunner.

Cooperating with cam surfaces 21 and 38 is a follower in the form of a carriage 47 comprised of two substantially identical parts 48 and 49, which, in the form chosen to illustrate this invention, may be of substantially triangular form in side elevation and made from plate stock which has been shaped at one corner Si) to provide a reduced thickness thereat. When the two parts 48 and 49 are placed in reverse relation to one another as shown in FIG. l0, a space 51 is formed 4between them into which extends one end of a spring retainer 52. Said parts 48, 49 and the intermediate spring retainer are connected together by a pivot pin 53 which may be a shoulder bolt passing through said parts and retainer 52. The reduced sectioned corners 50 of the parts 48 and 49 pivot about pin 53. The lower regions of carriage parts 48 and 49 are adapted to ride on cam surfaces 21 and 38. To reduce the force of friction which may be developed between the carriage parts and the cam surfaces, the said parts may be provided with suitable rollers 54 (FIG. 5) which ride upon said cam surfaces 21 and 38.

Carriage 47 is maintained in contact with cam surfaces 21 and 38 by a spring 55, the upper end of which, as viewed in FIGS. 1 and 2, bears against a flanged spring retainer 56 (FIG. 6). Part 12 has an internal boss 58 formed in the upper part thereof through which extends an adjusting screw S9 threadedly received in said boss 58 and fixed in any selected position by a lock nut 60 to function as an abutment for spring 55. Spring retainer 56 has a recess 57 in which the rounded end of adjusting screw 59 is received.

In the normal relaxed position of the recoil mechanism described above the parts will assume the relations and positions shown in FIG. l. Spring 55 in this gure has exerted pressure on carriage 47 to cause said carriage to ride downward upon cam surfaces 21 and 38, thereby causing parts 12 and 13 of the gunstock to move apart, the movement being limited by contact between heads 36 on shoulder bolts 33 and blocks 27 and 28. When a shell is exploded in the gun 11, the reaction of the explosion is carried back to part 12 and through its cam to the carriage 47, the parts 48 and 49 of which serve as thrust members. From the carriage 47 the reaction is transmitted to spring 55 through cam 37 to part 13. Since part 13 is held against the shoulder of the gunner and therefore is relatively stationary, the force of the discharge will cause the carriage parts 48 and 49 to roll along their respective cam surfaces 21 and 38 against the resistance of spring 55, and this will, in turn, cause the angularity between said carriage parts to decrease. As the angularity between the parts decreases, pivot pin 53 and its spring retainer 52 will be moved upward as viewed in FIGS. l and 2 toward the upper regions of parts 12 and 13. The resulting compression of spring 55 absorbs a substantial part of the force of the exploding shell. The disposition of the parts of the recoil mechanism at the height of the recoil is shown in FIG. 2.

Thus, the energy of the exploding shell imparted to gun barrel 11 and to gun stock part 12 is dissipated almost entirely in the compression of spring 55. The longitudinal or fore-andeaft force of the explosion, which normally would be felt by the shoulder of the gunner, is transformed into a vertical force acting against a spring, with the shape of the cam surfaces 21 and 38 controlling the rate at which spring 55 is compressed.

It may be noted that the angularity of the cam snrface relative to the general axis of spring 55 changes as carriage 47 rides up said cams. Thus, as the spring is compressed, thus requiring greater pressures for a unit deformation thereof, the angularity of the cams becomes more favorable for the creation of these pressures with a decreasing fore-an-d-aft force. The rate at which the spring is compressed can be altered by rotating one or both of the cams 20 and 37 about its respective pivot 22 and 39 in the desired direction and fixing said cams in such position with their respective set screws 23 and 26 on the one hand and 42 and 43 on the other. This changes the divergence of the cams 28 and 37 relative to one another. Said set screws are accessible from the exterior of the gunstock so that such adjustments can be made at any time. Similarly the force exerted by spring 55 may be changed by changing the initial compression of said spring as determined by set screw 59. Said set screw 59 is likewise accessible from the exterior of the gunstock and hence the initial compression of spring 55 can be altered at will without disassembling the stock.

The attachment of the gunstock 10 to the gun 11 can be effected in any one of a number of diierent ways. Thus gun 11 may have secured thereto, or formed integrally therewith, a stub 61 to which is secured a metal gib 62 adapted to interlock with a corresponding carriage part 63 formed integrally with part 12. The gib and carriage part may then be locked together by a set screw 64.

The recoil mechanism described above may be rendered inoperative by a pin (not shown) which is passed through aligned openings 65, 66 in the side walls 29 and 30 of part 13 behind the heads 36 of the shoulder bolts 33 and 34, thus preventing said bolts from moving backward relative to part 13.

In the form shown in FIGS. 8 and 9 the cams are xed and adjustment of the spring pressure is obtained by varying the effective height of the carriage. In these figures the gun stock parts are designated by the reference characters 12 and 13 and the cams are shown at 67 and 68 as integral parts of gunstock parts 12 and 13', respectively. They are thus unchangeable and present fixed cam surfaces 69 and 70 to the carriage 71. Said carriage 71 is comprised of substantially identical sections 72 and 73. Said sections are each split to form a base 74 and a triangular apex 75 connected together by pins 76 and 77, the latter in the form chosen to illustrate this invention being iixed to apex 75 and slidable in holes 78 and 79 in base 74. The spacing between base 74 and apex 75 is determined by an adjusting screw 80. It is understood that section 73 is identical in construction to section '72.

Sections 72 and 73 are connected at their apices by the pin 53 which also connects them to the spring retainer 52. Bases 74 are also provided with rollers 54 which ride on cam surfaces 81 and 82. Thus cams 67 and 68, carriage 70 and spring retainer 52 function in exactly the same manner as the corresponding parts of the form shown in FIGS. 1 and 2. Instead of varying the angularity of the cams 81 and 82, the distance between pivot pin 53 and the cams is varied. This has the effect of changing the initial location of the carriage 70 on the cams. If, for example, this distance is increased, carriage 70 will move down on the cams and cause a greater initial separation of the cams and their associated gunstock parts. At the lower position the cam contours are steeper and the effect is the same as tilting the cams upwards, and the opposite effect will be reached if the distance between the pivot pin 53 and the cams is decreased.

To provide access to the adjusting screws 80 gunstock part 13 is formed with an opening in its side which is normally closed by a pivoted door 84.

In both forms the fore-and-aft force of the exploding shell is transformed in part into a force acting in a transverse direction by the carriage and associated spring 5S, The transversely directed force is absorbed by the upper and lower walls of the gunstock parts through spring 55 and is not felt by the gunner. The reduced component which does act in the direction of the gunners shoulder is so diminished in magnitude that it is scarcely felt. At the instant the shock is created, spring 55 is extended to its maximum height at which the force required per unit of deection is at a minimum. As the carriage rides up on the cams, the angle of the cam changes so that although increasingly greater force is required to deect the spring, such force is created by the increasingly favorable wedging angle of the cams. The movement of the gunstock part 12 or 12 is thus smooth and continuous until the energy of the shock is dissipated. This is best illustrated in FIG. 11 where cam surface 82 is reproduced and the defiection of the spring DEF is shown for equal increments of displacement DISP of a point horizontally on the cam surface. It is readily apparent from FIG. 11 that as the point moves from left to right therein, the spring deliection becomes smaller and smaller, that is, as the shock loses its energy, less energy is required to defiect the spring and hence the movement of the carriage is smoothly brought to a halt.

After a shock has been dissipated, the continued pressure of the spring on the carriage provides a restoring force to separate the two gunstock parts. The separation continues until the heads 36 abut upon the bosses 27, 28. There is enough friction between shoulder bolts 33, 34 and their respective blocks, and between the carriage parts to dampen the action of spring 55 and prevent chattering of the two gunstock parts.

It may be understood that although the invention has been described with reference to its application to firearms, it may be applied with equal facility to machinery and to mobile equipment spring suspensions including cars, trucks, landing gears for planes, etc. It is understood therefore that the scope of this invention is not to be limited thereto, but is to be determined by the appended claims.

I claim:

1. A shock absorbing mechanism comprising spaced action and reaction members, a cam on each member, each said cam having a surface of a continuous curvature and said cam surfaces diverging with respect to one another, a follower contacting both cam surfaces simultaneously, an abutment on one of said members, and spring means connected to said abutment and said follower to hold said follower against said surfaces, whereby to deflect said spring at a rate which is different from the rate of movement of the action member relative to the reaction member.

2. A shock absorbing mechanism as described in claim 1, and means interposed between one of said cams and its member for changing the divergence of said one cam surface relative to the other.

3. A shock absorbing mechanism as described in claim 1, and means interposed between each cam and its member for changing the divergence of said cam surfaces relative to one another.

4. A shock absorbing mechanism as described in claim 1, said cam surfaces being disposed to diverge with respect to a line extending transversely of the direction of movement of the action member, and said spring means having its axis disposed generally along said line, such that shocks imparted to the mechanism in one direction are absorbed by said spring means in a direction having a component transverse thereto.

5. A shock absorbing mechanism comprising spaced ac- .tion and reaction members movable toward one another,

a cam on each member, each said cam having a surface of continuous curvature, said cams being spaced from one another and disposed with their said surfaces opposed to one another and diverging from one another, a follower riding on both said surfaces simultaneously, said follower comprising a pair of thrust members of substantially triangular form, a pivot connecting corresponding apices of the thrust members together, each said triangular thrust member having a two-point contact with a cam, and resilient means holding said follower against the cams, said resilient means reacting in a direction transverse to the direction of movement of the spaced action and reaction members whereby to divert a portion of the shock to a direction transverse to said direction of movement of the action and reaction members.

6. A shock absorbing mechanism comprising a relatively fixed member, a member movable toward the fixed member in response to a blow impressed thereon, guide means connecting the two said members and controlling the movement of the said movable member, a cam on each member, said cams having smooth continuous cam surfaces thereon in opposed relation to one another and diverging from one another, a follower riding on both cam surfaces simultaneously, said follower comprising a pair of thrust members of substantially triangular form, a pivot connecting corresponding apices of said triangular thrust members, each said triangular thrust member having a two-point contact with a cam, said triangular thrust members pivoting with respect to one another as the movable member and its cam moves toward and away from the fixed member, resilient means for holding said follower against said cams and restraining said pivotal movement, said resilient means being fixed at one end to one of said relatively fixed and movable members" and exerting a thrust in a direction transverse to the direction of relative movement of the relatively fixed and movable members, whereby to divert a portion of the shock in a direction transverse to said movement.

7. A shock absorbing mechanism as described in claim 6, and means for changing the disposition of the cams relative to one another to change the rate of deflection of the resilient means for a given movement of the relatively fixed and movable members relative to one another.

8. A shock absorbing mechanism as described in claim 6, and means for changing the shape of a thrust member to change the initial deflection of the resilient means.

9. A shock absorbing mechanism as described in claim 6, each said thrust member being comprised of two parts, and adjustable means connecting the two parts together.

10. A shock absorbing mechanism as described in claim 6, each said thrust member being comprised of two parts, pins connecting the parts together for sliding movement relative to one another, and screw means connecting said parts for adjustably holding said parts a predetermined distance apart.

11. A shock absorbing mechanism as described in claim 6, pivoted means mounting a cam on its member, and means for adjustably fixing the disposition of the cam on its pivot.

12. A gunstock comprising spaced first and second parts, means connecting said parts for relative sliding movement of one part relative to the other of said parts, and a shock absorbing mechanism interposed between and concealed within said parts, said mechanism comprising a cam on each part, each said cam having a surface of continuous curvature and said cam surfaces diverging with respect to one another, a cam follower contacting both surfaces simultaneously, an abutment on one part, and spring means connected to said abutment and said follower to hold said follower against said surfaces, whereby to deliect said spring at a rate which is determined by the curvature of the cam surfaces.

13. A gunstock as described in claim 12, each gunstock part being hollow, a cam in each part, a pivoted support for one of said cams in its said part, and means on its said part for adjusting the angular position of said one of said cams on its pivoted support.

14. A gunstock comprising a hollow first part, a hollow second part telescoped into the first part, guide means connecting the first and second parts and controlling telescoping movement of the second part into the first part, a cam in each part, each said cam having a continuous surface and said surfaces being disposed to diverge from one another in a plane transverse to the direction of the telescoping movement of said second part into the first part, a follower engaging both members, said follower comprising a pair of triangular thrust members, a pivot pin connecting the apices of said thrust members, spaced rollers on each of the thrust members, the rollers of each thrust member riding on its respective surface, a pivot on each part for supporting the cam therein, screws on each side of the pivot and bearing against the cam to adjust the angular position of the cam in its part, a spring retainer secured to the pivot pin, a spring retainer adjustably secured to the second part, a helical spring compressed between said spring retainers and exerting pressure upon the thrust members to hold them against the cam surfaces and resist telescoping movement of the parts, and means for limiting the separation of the said first and second parts.

References Cited by the Examiner UNITED STATES PATENTS 3,001,312 9/61 campbeu 421-74 'FOREIGN PATENTS 866,883 6/41 France.

6,030 1908 Great Britain.

BENJAMIN A. BORCHELT, Primary Examiner. 

12. A GUNSTOCK COMPRISING SPACED FIRST AND SECOND PARTS, MEANS CONNECTING SAID PARTS FOR RELATIVE SLIDING MOVEMENT OF ONE PART RELATIVE TO THE OTHER OF SAID PARTS, AND A SHOCK ABSORBING MECHANISM INTERPOSED BETWEEN AND CONCEALED WITHIN SAID PARTS, SAID MECHANISM COMPRISING A CAM ON EARTH PART, EACH SAID CAM HAVING A SURFACE OF CONTINUOUS CURVATURE AND SAID CAM SURFACES DIVERGING WITH RESPECT TO ONE ANOTHER, A CAM FOLLOWER CONTACTING BOTH SURFACES SIMULTANEOUSLY, AN ABUTMENT ON ONE PART, AND SPRING MEANS CONNECTED TO SAID ABUTMENT AND SAID FOLLOWER TO HOLD SAID FOLLOWER AGAINST SAID SURFACES, WHEREBY TO DEFLECT SAID SPRING AT A RATE WHICH IS DETERMINED BY THE CURVATURE OF THE CAM SURFACES. 